The present disclosure relates to wireless networking and ad hoc group calls therein. Broadband Push-to-Talk (PTT) to Project 25 (P25) interoperability is achieved using the P25 Inter Radio Frequency (RF) Subsystem Interface (ISSI) as a Network-to-Network Interface (NNI) protocol. The ISSI interface allows bridging mobile-to-mobile calls and group calls (either side can home the group) from broadband networks to P25 networks. Ad hoc group calls are a feature on broadband PTT such as the Open Mobile Alliance (OMA) Push-to-Talk Over Cellular (PoC), and Motorola's Proprietary PTT, etc. When a broadband user sets up an ad hoc group call by selecting one more contacts and/or one or more groups, the call is made to the superset of all contacts and groups. When an NNI protocol like OMA PoC is used for making an ad hoc group call, the list of all parties in the remote system can be sent in one Session Initiation Protocol (SIP) INVITE. This facility is not present in ISSI. As a result, for example, when a broadband user makes an ad hoc group call by selecting 10 P25 Subscriber Units (SUs), there are 10 ISSI call legs initiated to the P25 network, and assuming the 10 P25 SUs are at a same site, today this results in 10 channels being used up at the same site for one call.
Accordingly, there is a need for a method and apparatus for improved resource allocation in ad hoc group calls.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.